BAP1 gene mutations in Egyptian patients with advanced sporadic malignant pleural mesothelioma (MPM): relation with clinical outcomes and survival.

Background: Malignant Pleural Mesothelioma (MPM) is a lethal cancer with few therapeutic options. Patients with MPM have a poor prognosis, with estimated 1 year median survival and currently no treatment is curative. The BRCA associated protein 1 (BAP1) has the highest prevalence of protein-altering mutations identified in MPM.

Aims: Assessment of the frequency and pattern of BAP1 gene mutations in Egyptian patients with advanced sporadic MPM in relation to disease progression and survival rates in order to identify a novel therapeutic target for MPM.

Methods: This prospective, cohort study included 122 patients who were diagnosed and treated as advanced MPM. BAP1 gene mutations were assessed from circulating tumor cells (CTCs) by polymerase chain reaction (PCR) and sequencing and these mutations have been confirmed using the tumor tissue. BAP1 immunohistochemistry was performed using the Dako Envision visualization system. The relationship between BAP1 gene mutations, PFS and OS rates was assessed using the log rank test. The relationship between BAP1 gene mutations, clinical response and patient's clinicopathological characteristics was assessed using chi-square test.

Results: Forty seven (38.5%) MPM cases showed one or more mutations in BAP1 gene. The presence of BAP1 mutations associated significantly with BAP1 protein expression (p < 0.001), the incidence of organ metastasis (p = 0.04), PFS after second line treatment (p = 0.04) and clinical response after second line treatment (p = 0.01) only.

Conclusion: BAP1 gene mutations are relatively common in Egyptian patients with advanced sporadic MPM. BAP1 mutations are associated with disease progression especially after second line therapy and the incidence of organ metastasis.